In known high power, high speed gearbox applications, such as transmission gearboxes for helicopters, typically planetary gear sets are utilized. Generally, planetary gear sets utilized in these applications have straight, in-line input and output axes. Therefore, to have an output that is not in-line with the input different gear sets must be employed to alter the direction of the output with respect to the input direction. Additionally, to achieve low speed outputs from high speed inputs, significant gear reduction ratios are needed that require various stages of gears to be incorporated within the gearbox. Furthermore, to alter the direction of output of gearboxes utilizing planetary gear sets, additional idler gears need to be added. These additional gears and/or gear sets significantly increase the complexity, weight and manufacturing and repair costs for such high speed planetary gear set gearboxes.
Face gears are currently used for many applications throughout industry. However, face gears are typically implemented in low power, low speed applications. For example, face gears are commonly utilized in cement mixer trucks that use higher strength course tooth face gears to turn the large barrels; satellite applications that incorporate large diameter fine tooth face gears for precise indexing of equipment; and large ship propeller drives. Inexpensive nylon face gears are also being used in commercial items such as fertilizer spreaders. Recently, attempts have been made to utilize face gears in high power, high speed power transmission applications. However, typically the use of face gears in such high power, high speed applications has been limited by such things as the complexity of employing off-line input/output axes angles other than 90° and the general necessity to incorporate additional idler gears to change the rotational direction of the output.
Therefore, it is desirable to provide a gearbox incorporating a high power, high speed gear set that will allow for off-axes input/output implementations, provide high input/output gear ratios and provide the capability to change the rotational direction of the output while minimizing the number of parts and, thereby, significantly reducing the cost of manufacturing and repair of such gearboxes.